How many space heaters to keep house from freezing?

Surely there's someone here that has a data point for me. I'm currently 1400 miles from home and it seems the big storms killed my power at home on Sunday. My Dad was not able to stop over to check on the house until late last night (he works 2nd) and the power was out long enough to kill my boiler Sunday. As of 11 am today the house was at 42F.

My dad was unsuccessful at getting the boiler relit last night. He's stopping by tonight to try to light it again now that he's better prepared. Hopefully it'll take off but I'm working on backup plans.

House is ~1500 sq ft, ranch with full basement, built in 73 in NE ohio. House would have been ~65 Sunday afternoon when the power went out. Temps were high of 27, low of 19 Monday and Tuesday. Today was high of 37 so I expect the house is still around 40F currently.

Expected forecast is shown below. Working on a backup plan to keep the pipes from freezing until Saturday when I know I can get someone to get the boiler lit if my Dad doesn’t get it tonight.

There are 4 main places I’m concerned about freezing pipes.  Bathroom/laundry room at west end of house, kitchen in middle of house, main bathroom in hallway, and master bath at the other end of the house.

If I get a 1500 watt space heater in each of those locations, do I have a chance to keep it above freezing or am I wasting my time?  I figure someone here has heated a garage with a space heater before and can give me an idea about square footage it can keep above freezing.  All the info I’ve found online has been what it takes to heat to 70F, not 45F.

Thanks in advance for any info.

As i remember they are good for roughly 100-150 sq ft each but in reality its good for about half that.

If it isnt a well insulated house, my guess would be a lot. 2 each in bathrooms and kitchen minimum. Garage would be as many as possible probably. going down to 42 in 4 days doesnt sound like its got great insulation. My lake house doesnt get that low for weeks when i brought the house up to 65 for 4 hours

They also arent exactly the safest thing to just leave running without anyone nearby too

Basement or slab? if the power is out how do the spaceheaters work? start the faucets dripping ?

I'll give my unscientific answer:  zero.

19 degrees would take weeks to freeze most plumbing.  I wouldn't sweat it until the 4th.

My furnace died this winter and it took a week to get the part.  Lows every night ranged from 18 to 27.  Daytime highs ranged from 25-40.  I went and stayed at my girlfriend's for the week.  Tiny 856 sf single story house built in the 20s with only a 12' x 20' basement.  Monitoring my Nest thermostat, the lowest it got inside the upstairs all week was 43.  I stopped in to check things and set up a 1500w space heater in the basement, but when I went downstairs it felt warmer than upstairs.  I set the space heater to 50 (its lowest setting) and it didn't turn on.  I went back to the warmth of the lady's house.  I'm not even sure the heater ever kicked on.

My only concern was the bathroom.  It is about 12' out from the basement above a crawlspace and the water supply for the toilet is on an exterior wall.  Never had an issue.

Two other things.  I have a 5 gallon bucket outside for smokers to throw their butts.  It is of course full of water.  After all the below-freezing weather we've had, only about the top 2" was frozen.  When I full-timed in an RV, I didn't even worry about it unless things were going to be below freezing for a long time.  An overnight at 28?  Meh.  Let a faucet drip.  Three days of 25 in an RV?  Yeah, then I worry.

In reply to TRoglodyte :

Basement, poured concrete.  The power only went out long enough for my fire to go out in my boiler, it's currently on.

I told my Dad to start the faucets dripping if he doesn't get it going tonight.  Most of the plumbing is in the basement which should stay pretty warm but the west bathroom/laundry room and the kitchen sink are both on outside walls.

In reply to Curtis :

Part of me says it'll be fine till the weekend, tonight and tomorrow night are my biggest concerns.  

I understand the safety aspect of what I'm asking.  I would normally never leave a space heater plugged in when I wasn't there.  My thought was the oil filled radiators would be the safest way to go, my biggest concern is if two were on the same breaker, my house is wired kinda funny.

In reply to Dead_Sled :

I’m sick or i’d go light the house on fire for you to keep it warm 

In reply to Patrick :

Just make sure you move the cars away from the house first!

A good friend here blew a pipe on an exterior wall when he lost heat for a couple days.  His house was in the 40s, but the pipe was below the main floor so it was in uninsulated space.  It was not anywhere near as cold as your forecast.

Can you just put pipe heating tape/cable on each of the pipes on an exterior wall?  Or even better, just along lengths of it in the basement closest to the outside walls?  Heating the whole house to keep a few pipes from freezing seems both difficult and inefficient.

Where are the pipes in the garage? (what wall?)

The house rooms are easy.  Oil heater set to 45f and shut the door and you wont have any problem keeping them above freezing.  If you can get one that has multiple settings, do that as you can keep it on low and you will be less likely to pop a breaker.

I agree with Curtis. I don’t think you really need to worry about pipes freezing. If you have shutoff valves in the bathrooms and kitchen, turn them off. 

Id probably stick one in the basement, far bathrooms, and the kitchen. Open all cabinet doors that have plumbing underneath them. Honestly though, it’s mostly because I wouldn’t want to wait for the house to warm up when I get home. 

Dead_Sled said:

In reply to Curtis :

Part of me says it'll be fine till the weekend, tonight and tomorrow night are my biggest concerns.  

I understand the safety aspect of what I'm asking.  I would normally never leave a space heater plugged in when I wasn't there.  

I kinda went through the same thing when my furnace died.  Which is worse? a burst pipe or a 900 square foot pile of ashes?  ... and what are the odds of one or the other happening?  I ended up using my space heater for a just-in-case thinking that the tiny little cube heater didn't have enough combustible material to light the subfloor on fire 7 feet above it.

I was so thankful for my wifi thermostat.  The house only has one and it's centrally located.  I figured if the upstairs temps hit 32 I would go home and do something.  This of course wouldn't have helped if the power went out because my house would lose wifi (backup battery for wifi and an internal battery on the thermostat) after about 2 hours and I would be clueless.

My house has a gas forced air furnace and a single baseboard electric heater in the mudroom/laundry room set to minimum.  As long as I have power, I'm good.  If I lose power for an extended time while I'm away, I'm screwed.  I am currently planning a fireplace install so if I'm home and lose power for a long time I can just build a fire.  I guess you would call that "analog" heating.  Get it?  Log?  Nevermind.

I shut off the main water valve.  My thought was, that limits the chances of water damage to just the stub of pipe that comes in the basement.  The chances of it freezing were slim since it is below frost line (obviously) and was in a basement that is insulated by being about 7' deep into the ground.  I had no way of draining the lines in the house without cutting just after the valve, but at least I could turn on the main and check for busted lines.  If anything leaked, I could go turn off the water again in 30 seconds instead of coming home to a week of water damage.

In reply to ProDarwin :

I've thought about the heat wrap, but I'm still concerned about toilets.

I'm not worried about most of the rooms, the only water into any rooms other than listed above is just the boiler water system, which I expect to stay at or near the basement temp since the boiler is currently a big thermal mass at the basement temperature.  

These are the best heaters I've been able to find in stock nearby.  It's surprisingly hard to find these in stock.

https://www.tractorsupply.com/tsc/product/redstone-multi-purpose-oil-filled-radiator-heater

No concerns about the garage, the water comes from the basement through an interior wall, should be at basement temp.

In reply to mtn :

SWMBO has already asked to be dropped off at her moms while I go heat the house up.

This does give me an idea though.... the wifi thermostats often come with slightly cheaper remote sensors.  Maybe you could do a Nest (or similar) and get an add-on sensor that you strap to the most vulnerable pipe.  That way you could monitor the pipe's ambient temperature while you sip on a Grillmarkaðurinn in Reykjavik. 

In reply to Curtis :

The main shutoff is still on because I never turn the water off if the boiler is going, it needs to be able to top off the boiler water if the prv releases some pressure/water.  Air in a boiler is bad news.

Many of the fixtures in my house do not have shutoffs installed upstairs, they're below the floor in the basement.  If the temp is dropping and the boiler is out I'll have them shut off the main valve, I'm much less worried about replacing plumbing than I am about a flood.

In reply to Curtis :

We unfortunately do not have home internet beyond our phones.  If I could monitor house temps remotely I'd be much less worried.

A few years ago my furnace quit on a -20F night.  My house is pretty large, and was built in 1913 so it's not particularly well insulated or weathertight.  I scrambled around and was able to borrow a half dozen space heaters from neighbors, and they kept the house above 50 degrees until I got a repair guy out the middle of the next day.  I also set up a couple box fans to help circulate the air from the heaters, and turned on every light in the house to get a little more heat (but this really only works if you still have incandescent bulbs.)

The furnace has been fine ever since but I'm a little paranoid about it, so whenever I've found a space heater at a yard sale for cheap or free I bring it home.  I now have a stack of them in the corner of the basement, just in case.  

Turn the oven on for a few hours.  And or some pots full of water on the burners.

Pete

NOHOME said:

Turn the oven on for a few hours.  And or some pots full of water on the burners.

 

Pete

I do the oven trick quite frequently at my lake house, works fine but obviously dont leave it

If you do end up getting space heaters, get the “milkhouse” style. They’re typically the cheapest and last the longest. One in each of the rooms you’re worried about, pointed in the general direction of the plumbing, will work perfectly. 

FWIW - our old house in IL(built in 1878) had zero heat in the entire upstairs, and was where our bedroom + half bath were located. There was zero insulation in the walls or window casings, and minimal in the attic. I tried many different types of space heaters over the 8-years I lived there & the milkhouse ones simply work best, last the longest, and were normally the cheapest. 

I had an uninsulated 1928 2-story house and the heat went out for a few days. I had three oil filled radiators and they kept the house at about 40-45 degrees in temperatures like you describe. No problems with frozen pipes. No pipes were in exterior walls thankfully. 

You said you have a boiler, so lets go with the fact that you have baseboard heat.  I'm also going to assume you have a tankless water heater on that boiler.  You need to make sure the boiler has power and the circulator pump is running.  Moving water will not freeze.  That will also help to keep the rooms all stay relatively the same temp.  Pick up one or two space heaters.  Keep all of the doors inside the house open.  Keep the drapes open in any windows facing the sun.  Run the water in the faucets until the water temp equalizes to ground temp which should be around 52*.  Fill the bath tub and kitchen sink with water.  It will act as a heat sink. Have your dad come by once a day and drain the water, run the water, fill the bath tub again.  Put some non toxic RV antifreeze in the toilet bowl and tank.  Heat pipes and toilets always seem to be the first to freeze.  You will be fine.  This is one instance where you should be glad your on a slab and not in an old house with a stone foundation and a big drafty basement.

So stupid question but why not pay an HVAC dick to come over and start the boiler.  $200 or so for an hour service call sure seems easier than all this screwing around?  Plus you know its handled correctly.  

First, good news is Dad was able to get the boiler lit up last night.  House was still at 42.

I would have gladly paid a professional to come light it, but I run a coal boiler in the middle of ohio, the only guy I'd know to call is my coal guy who is 70 miles away.  He would have been the guy coming Saturday if my Dad wasn't able to get it going.

I realized my Dad had not lit the boiler in more than 5 years.  Lighting coal is not as easy as lighting a wood fire.  There's many ways to do it but they all take a little technique to get it going.  I'm sure he'd tell you it was easy once he got it going.